That indicates that your food may have not been fully digested yet (due to lack of gastric acid)
and sitting in the intestines
and fermenting, with
gas as a byproduct.
Also, if you have low gastric acid, there's a good chance you may have SIBO (small intestinal bacteria overgrowth) which also causes gas, bloating or burping etc.
But, you don't have to take my word for this.
All you have to do is a Betaine HCL trial
(very inexpensive)l, as a test.